The deregulation of miR-155, a highly oncogenic microRNA (miRNA), has been associated with a wide variety of malignancies including lung cancer. Non-small-cell lung cancer (NSCLC) is the leading cause of cancer- related death in the US with dismal clinical advances to improve patient?s survival, due to the development of drug-resistance. We have demonstrated that miR-155 plays a role in mediating resistance to chemotherapy in NSCLC. Treatment with anti-miR-155-DOPC significantly reduced tumor growth and resensitized NSCLC to standard of care platinum-based chemotherapeutics with no toxicity in an in vivo orthotopic mouse model. miR- 155 acts on a TP53-dependent mechanism, triggering a feedback loop leading to chemotherapy resistance. Tumor microenvironment (TME) plays an important role in the promotion of cancer, specifically via monocyte/macrophage cells that express high levels of miR-155 by exosomal transfer with cancer cells. We developed nanoliposomal-bound aptamers to specifically target the AXL receptor, significantly overexpressed by NSCLC tumor cells and expressed also by monocyte/macrophage cells, in addition to targeting miR-155. By complementing standard interventions that have life-threatening toxicities with anti-miR-155 in nanodelivery vehicles (like single-lipid nanoliposomal particles, SLNPs), which we anticipate to be safe and non-toxic, we expect our findings to change treatment regimens for NSCLC. The main goal of this MPI revised application is to perform preclinical safety and toxicity studies to test the efficacy and safety of adjuvant anti-miR-155 therapies, coupled with SLNP-anti-miR-155 or AXL-Apt-SLNP-anti-miR-155, alone or in combination with cisplatin and vinorelbin. These preclinical studies will pave the way to an Investigational New Drug (IND) application for the use of anti-miR-155 treatment in NSCLC, and other chemotherapeutic resistant tumors. We plan to: 1) target miR-155 both in cancer cells and in TME by using the two types of SLNPs in NSCLC; 2) determine the toxicity of anti-miR-155 therapies based on the delivery using biocompatible nanodelivery in animal studies; 3) identify the full spectrum of miR-155 targets that could be therapeutically exploited and used for reducing toxicity; 4) develop novel mathematical models to determine the therapeutic value of anti-miR-155 treatment, based on multiple parameters, including circadian administration; 5) determine the in vivo antitumor efficacy of tumor targeted dual-effect AXL-Apt-SLNP-anti-miR-155 nanotherapeutics alone and in combination with chemotherapy in orthotopic and patient-derived xenograft models and, finally, 6) to compile the results for the IND application. The final outcome of our proposal would be to establish the efficacy of anti-miR-155 to treat NSCLC by directly targeting miR-155 in the tumor and TME in combination with existing chemotherapeutic treatments. We expect anti-miR-155 to significantly reduce the mortality of NSCLC without any major side effects, and also improve overall survival. Such studies can be further expanded for targeted therapeutic strategies, such as checkpoint inhibition, if these become the standard of care.